Recovery of tree and mammal communities during large‐scale forest regeneration in Kibale National Park, Uganda

Abstract

Tropical landscapes are changing rapidly as a result of human modifications; however, despite increasing deforestation, human population growth, and the need for more agricultural land, deforestation rates have exceeded the rate at which land is converted to cropland or pasture. For deforested lands to have conservation value requires an understanding of regeneration rates of vegetation, the rates at which animals colonize and grow in regenerating areas, and the nature of interactions between plants and animals in the specific region. Here, we present data on forest regeneration and animal abundance at four regenerating sites that had reached the stage of closed canopy forest where the average dbh of the trees was 17 cm. Overall, 20.3 percent of stems were wind-dispersed species and 79.7 percent were animal-dispersed species, while in the old-growth forest 17.3 percent of the stems were wind-dispersed species. The regenerating forest supported a substantial primate population and encounter rate (groups per km walked) in the regenerating sites was high compared to the neighboring old-growth forests. By monitoring elephant tracks for 10 yr, we demonstrated that elephant numbers increased steadily over time, but they increased dramatically since 2004. In general, the richness of the mammal community detected by sight, tracks, feces, and/or camera traps, was high in regenerating forests compared to that documented for the national park. We conclude that in Africa, a continent that has seen dramatic declines in the area of old-growth forest, there is ample opportunity to reclaim degraded areas and quickly restore substantial animal populations.

Natural forest regeneration and ecological restoration in human‐modified tropical landscapes

“…Agricultural fields must retain forest cover in their vicinity ( e.g ., live fences and other living structures acting as biological corridors) to facilitate the movement of pollinators, seed dispersers, herbivores, and other animals playing key roles in forest regeneration (Omeja et al . ). The area devoted to second growth forests would be retained for long time periods, as biodiversity and ecosystem functions and services of these forests increase with forest age (Chazdon ); enriching secondary forests with species providing valuable timber and non timber forests products, and developing sustainable and economically viable forest management programs for landowners, could help to reach this objective (Lamb et al .…”

“…, Muench & Martínez‐Ramos , Omeja et al . ) that play important ecological roles (as pollinators, seed dispersers, controllers/regulators of diseases, among other functions) in forest regeneration and maintenance of biodiversity in the landscape (Dirzo et al . , Latawiec et al .…”

Comparing seed removal rates in actively and passively restored tropical moist forests

“…Consequently, the passively restored forests have more low shrubby vegetation than actively restored forests. In the 21‐year‐old planted compartments, the mean number of species and diameter at breast height ([DBH], 1.3 cm) are 2.9 and 19.8 cm, respectively (Omeja et al ). The most common tree species are B. micrantha , S. elliptica , and Funtumia latifolia (Stapf) Stapf.…”

“…The most common tree species are B. micrantha , S. elliptica , and Funtumia latifolia (Stapf) Stapf. In comparison, the mean number of species and DBH in the natural forest are 85.0 and 24.7 cm, respectively (Omeja et al ).…”

“…The most common tree species are B. micrantha, S. elliptica, and Funtumia latifolia (Stapf) Stapf. In comparison, the mean number of species and DBH in the natural forest are 85.0 and 24.7 cm, respectively (Omeja et al 2016). The study sites were compartments located within: (1) actively restored forests (21-, 17-, 16-, 11-, 8-, and 6-year-old restoration plantings); (2) 21-year-old passively restored forests; (3) natural forests near the UWA-FACE station in Mainaro; and (4) grasslands (Kanyanchu, Isunga, Ngeza, and Mpokya) ( Table 1).…”